Fig. 273.—Ideal form of cuestas and intermediate lowlands carved from a coastal plain (after Davis).
The sudden uplifts of the coasts.—Elevations of the coast which yield the coastal plain must be accounted among the slower earth movements that result in changes of level. Such movements, instead of being accompanied by disastrous earthquakes, were probably marked by frequent slight shocks only, by subterranean rumblings, or, it may be, the land rose gradually without manifestations of a sensible character.
Upon those coasts which are often in the throes of seismic disturbance, a quite different effect is to be observed. Here within the rocks we will probably find the marks of recent faulting with large displacements, and the movements have been upon such a scale that shore features, little modified by subsequent weathering, stand well above the present level of the seas. Above such coasts, then, we recognize the characteristic marks of wave action, and the evidence that they have been suddenly uplifted is beyond question.
Fig. 274.—Uplifted sea cave, ten feet above the water upon the coast of California; the monument to a former earthquake (after a photograph by Fairbanks).
Fig. 275.—Double-notched cliff near Cape Tiro, Celebes (after a photograph by Sarasin).